Rotary pulverizer



Patented Oct. 16. 1923.

UNITED STATES PATENT OFFICE.

JAMES JOHN DENNY AND ROLLA BARNUM WATSON, OF COBALT, ONTARIO, CANADA.

ROTARY PULVERIZER.

Application filed December 3, 1921. Serial No. 519,593.

fication and illustrated in the accompanying drawings, that form part ofthe same.

The objects of this invention are to minimize the wear in pulverizing orgranu- 'lating machines such as used in the pulverizing of ores. therebylessening the cost of operation and obtaining the maximum service of themachine, and further to provide an improved liner for the machine whichwill be materially lighter than the formof'liners at present in use andwill therefore absorb less power.

A still further object is to obtain the maximum service from thegrinding me- 5 dium.

The principal feature of the invention consists in providing a liningfor rotating pulverizers of a resilient wear-resisting material. I

In the drawings. Figure 1 is a perspective view of the cylinder of aball pulverizer showing the preferred form of lining.

Figure 2 is a section perspective view similar to Figure 1 illustratinga different form of liner.

Figure 3 is'a diagrammatic illustration of a'ball mill showing thelocation of the balls in operation.'

In the practice of grinding of'ores it has been the custom to line ballgranulators and rotating tube mills with wear-resisting materials suchas manganese steel, white iron, silica blocks, etc., against which thegrinding medium in the form of steel balls or hard pebbles of flint orlike material impinge in the rotative action of the mill. Such types ofliners are extremely heavy and thereforerequire a considerable amount ofpower to rotate the mills. A considerable loss is sustained through thewear of the grinding medium operating against the extremely hard liners.These liners wear out very quickly and require the frequent shuttingdown of the machines for the purpose of renewal which in addition tomaterial cost results in a very heavy labor loss.

The present invention contemplates a radical change in that the liner isformed of a material of light weight having great resilience and highresistance to wear through the impact of heavy bodies thereagainst andwhen worn such linersmay be replaced at the minimum expense of time onaccount of the ease with which they may be handled.

This improved form of lining is preferably produced in the form ofstrips of rubber material substantially the same as that used for thetread rubber of automobile tires, which has been found in practice to bea very eflicient resistant to wear.

The strips 1 as illustrated in Figure 1 are placed around the innercircumference of the cylinder, the flexible nature of the materialallowing them to conform to the circular shape. A lining in such formrequires the minimum of fastening devices for bolding it in place. Ifdesired, the liner may be formed of a single slab of a width equal tothe length of the cylinder. If desired the liner may be formed of slabsor bars 2 of a suitable resilient material placed longitudinally of thecylinder as illustrated in Figure 2.

Alining formed of rubber material while sufliciently hard to resistwear, is of a very tough nature but ithassuflicient resiliency to causethe steel balls or other grinding medium to rebound therefrom uponimpact in such a manner as to avoid disintegration of the liner surface.Further, the rebounding action of the grinding media produces a verymarked increase in efliciency in the pulverizing of the ore between suchmedia.

' Such a lining is infinitely light in weight than those heretoforeused, consequently the heavily weighted mill will be greatly lightenedwith the result that much less power is expanded. Furthermore, thereplacement of. the rubber lining is a comparatively simple matter andmay be effected very rapidly.

What we claim as our invention is 1. In a rotary pulverizer, thecombination with the rigid shell and the loose grinding balls, of alining of resilient material interposed between the shell and the ballsand adapted to be temporarily depressed b the balls in immed a e c n acth w t.

during the rotation of the pulverizer, said ing balls, of a lining ofsemi-hard vulcanized resilient material by its yielding and fricrubberforming the inner wall of the shell tional character being adapted tocarry the and compressible under the weight of the 1 balls and thematerial upward with the mass of balls to form an undulating contact 5minimum amount of slippage. surface to lift the balls.

2. In a rotary pulverizer, the combina- JAMES JOHN DENNY. tion with therigid shell and the loose grind- ROLLA BARNUM WATSON.

